﻿using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Drawing.Imaging;

namespace Fsb.Utility
{
    public class ValidateCode
    {
        const int CODE_SIZE = 4;

        private string Code;
        private byte[] ImageBytes;

        private ValidateCode()
        {
            this.Code = this.CreateValidateCode(CODE_SIZE);
            this.ImageBytes = this.CreateValidateGraphic(this.Code);
        }

        //// <summary>
        /// 生成验证码
        /// </summary>
        /// <param name="length">指定验证码的长度</param>
        /// <returns></returns>
        private string CreateValidateCode(int length)
        {
            int[] randMembers = new int[length];
            int[] validateNums = new int[length];
            string validateNumberStr = "";
            //生成起始序列值
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
            Random seekRand = new Random(seekSeek);
            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
            int[] seeks = new int[length];
            for (int i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = 0; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum = 1 * (int)Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = 0; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成验证码
            for (int i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }

        /// <summary>
        /// 创建验证码的图片
        /// </summary>
        /// <param name="containsPage">要输出到的page对象</param>
        /// <param name="validateNum">验证码</param>
        private byte[] CreateValidateGraphic(string validateCode)
        {
            using (Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 14.0), 22))
            {
                using (Graphics g = Graphics.FromImage(image))
                {
                    //生成随机生成器
                    Random random = new Random();
                    //清空图片背景色
                    g.Clear(Color.White);
                    //画图片的干扰线
                    for (int i = 0; i < 25; i++)
                    {
                        int x1 = random.Next(image.Width);
                        int x2 = random.Next(image.Width);
                        int y1 = random.Next(image.Height);
                        int y2 = random.Next(image.Height);
                        g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                    }
                    Font font = new Font("Arial", 14, (FontStyle.Bold | FontStyle.Italic));
                    using (LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.4f, true))
                    {
                        g.DrawString(validateCode, font, brush, 3, 2);
                        //画图片的前景干扰点
                        for (int i = 0; i < 100; i++)
                        {
                            int x = random.Next(image.Width);
                            int y = random.Next(image.Height);
                            image.SetPixel(x, y, Color.FromArgb(random.Next()));
                        }
                        //画图片的边框线
                        g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                        //保存图片数据
                        using (MemoryStream stream = new MemoryStream())
                        {
                            image.Save(stream, ImageFormat.Jpeg);
                            //输出图片流
                            return stream.ToArray();
                        }
                    }
                }
            }
        }

        public override string ToString()
        {
            return this.Code;
        }

        public byte[] ToImageBytes()
        {
            return this.ImageBytes;
        }

        public static ValidateCode NewCode()
        {
            return new ValidateCode();
        }
    }
}
